Update readme.md

[wybiral]

The current examples/api/demoapp documentation has an error where it defines cfg twice using two different styles:

	cfg := &core.BuildCfg{
		Repo:   r,
		Online: true,
	}

	cfg := new(core.BuildCfg)
	cfg.Repo = r
	cfg.Online = true

This PR will make the documentation more consistent with the actual code.